* Fixed a bug in Ray.intersectObject: face.normal needs to be transformed using matrixRotation otherwise rotated objects fail
* A bit nicer example

Unimpressive example added `interactive_spheres.html`

The idea is that later there will be more loaders which would load different formats (like OBJLoader, ColladaLoader).

Usage (async JS):

var loader = new THREE.Loader();
loader.loadAsync( "obj/torus/Torus.js", function() { createScene( new Torus() ) } );

Usage (web worker):

var loader = new THREE.Loader();
loader.loadWorker( "obj/torus/Torus_slim.js", function( geometry ) { createScene( geometry ) } );

Web worker loader is useful for large meshes, where it allows browser to stay responsive for longer time and also it can handle larger meshes than async JS loader.

Web worker loader needs a simpler format of the model. Web workers can communicate with the main application only via message passing, where messages are JSON objects.

There is a new version of OBJ -> Three.js converter (convert_obj_threejs_slim.py) which can produce model in format needed for web workers.

All examples which were using models from OBJ converter were refactored to use Loader.

Except large mesh example, all examples are using just async JS loading. Web worker loading is there, it's just commented out, as it's a bit pain for local development.

Chrome doesn't allow to run web workers from pages accessed via file://, so you need either to run it with "--allow-file-access-from-files" flag, or access examples via local server (http://localhost/example.html).

Fixed ambient light computation in CanvasRenderer to get correct lighting when there is no ambient light specified in the scene.

* Projector.js: Rather than calculating the screen space centrium of each face per render, seemed smarter to just project the precomputed centrium. Side effect: Polygon shaking is gone \o/

Limitations:

 - Chrome can handle up to 5 lights in total (directional + point)
 - Firefox seems to handle up to 29 lights

These number are GPU specific (mine is ATI Mobility Radeon 3650).

This turned out to be quite tricky. The number of varying vectors in shaders is limited. Additionally Chrome and Firefox have different limitations (at least on Windows, probably due to Chrome using ANGLE as rendering backend).

Hence WebGLRenderer has hardcoded limit of maximum 5 lights.

WebGLRenderer constructor now takes (optional) scene argument, so that numbers and types of lights present in the scene can be used to generate minimal possible shader.

If no scene is passed, shader allowing 1 directional + 4 point lights will be generated.

* Added `camera_orthographic` example.

* Minor fixes (Geometry normal calculation)
* Isolated Matrix3 code into `Matrix3.js`
* README and TODO updated

In Chrome it looks more or less ok, but it has some problem in Firefox 4 (with some camera angles there are black areas around edges).

Also updated Python builder scripts and examples to include this new material.

* MeshBitmapUVMappingMaterial -> MeshBitmapMaterial. Second param is mode, which is THREE.MeshBitmapMaterialMode.UVMAPPING by default.
* Removed MeshFaceColorFillMaterial and MeshFaceColorStrokeMaterial
* Added MeshFaceMaterial ( it uses the face.material for that pass )
* CanvasRenderer and SVGRenderer per face material logic changed.
* SVGRenderer supports particles again.
* WebGLRenderer currently broken :/
* Code clean up

Refactored multimaterials to also work with non-textured models composed from multiple material groups.

Old version was doing massive overdraw (whole mesh was drawn for each material).

Even current solution is still quite messy: there is a different behavior for stroke and fill materials (when used as secondary materials).

Stroke materials are applied to the complete mesh (as most common use case seems to be wireframe) while fill materials now apply only to faces within single material group (when "decalIndex" property of secondary fill material is set).

Extended CanvasRenderer to be able to handle decals (MeshBitmapUVMappingMaterials as secondary materials).

For decals you need to set "decalIndex" property of the material (corresponding to materials index of the original mesh UV material).

Added multimaterials example.

Fixed forgotten sphere smoothing in OBJ converter example.

Added OBJ converter test example.

Modified Three.js to handle converted models:

 - extended WebGL renderer to use texturing
   - broke down model into multiple VBOs according to materials
   - textures are lazy created when images get loaded
     (converter takes care of resizing images to nearest power of 2
      dimensions using 2d canvas)

 - changed material array semantics in Mesh object
    - before: multiple materials were applied to all faces (broken in WebGL, needs multitexturing shader)
    - now: there is only single material per face, but one mesh can have faces with different materials

 - added per vertex normals (to get smooth shading in WebGL)

* `CanvasRenderer` and `SVGRenderer` basic lighting support (`*ColorStroke`/`*ColorFill` only)
* `Renderer` > `Projector`. `CanvasRenderer`, `SVGRenderer` and `DOMRenderer` do not extend anymore
* Interactivity base code (hdi folder). To be refactored... ([mindlapse](http://github.com/mindlapse))
* Added `computeCentroids` method to `Geometry`
* Included `Stats.js` directly in the `/examples` folder to avoid the need of internet for playing around

- Minor tweaks

* Additional `Matrix4` and `Vector3` methods

- Camelcased the minified files (it feels weird both ways anyway...)

- Face4 with MeshBitmapMaterial gap fixed

- `three_debug.js` checks for broken UVs and display these faces with pink color instead

* `Face4` now supports `MeshBitmapUVMappingMaterial`
* Changed order of `*StrokeMaterial` parameters. Now it's `color`, `opacity`, `lineWidth`.
* `BitmapUVMappingMaterial` > `MeshBitmapUVMappingMaterial`
* `ColorFillMaterial` > `MeshColorFillMaterial`
* `ColorStrokeMaterial` > `MeshColorStrokeMaterial`
* `FaceColorFillMaterial` > `MeshFaceColorFillMaterial`
* `FaceColorStrokeMaterial` > `MeshFaceColorStrokeMaterial`
* `ColorStrokeMaterial` > `LineColorMaterial`
* `Rectangle.instersects` returned false with rectangles with 0px witdh or height